Addressing High-Voltage Design Challenges With Reliable and Affordable Isolation Technologies
The first priority in any high-voltage power system is to protect maintenance personnel and end-equipment users. Galvanic isolation satisfies this priority by isolating the high voltage from other low-voltage human interface sections.
The second priority is to establish reliable and safe operation between high- and low-voltage circuits, such as voltage and current sensing, power-supply control, digital communication and signal processing. Reliable isolation techniques, materials and ICs allow designers to satisfy this priority.
At a glance
This paper provides an overview of galvanic isolation, explains common isolation methods for high-voltage systems, and shows how Texas Instruments (TI) isolation integrated circuits (ICs) can help designers meet isolation needs reliably while reducing solution size and cost.
| 1 What is galvanic isolation? | Galvanic isolation introduces electrical partitions that prevent current from flowing between
two or more parts of a system. Isolating signals and power protects
personnel and equipment and adheres to industry and international
standards. |
| 2 High-voltage galvanic isolation concerns | and methods Learn the primary considerations when constructing an isolation barrier, such as voltage
ratings, spacing dimensions, common-mode transient immunity (CMTI) and
electromagnetic interference (EMI). |
| 3 Achieve isolation needs reliably while reducing solution size and cost | Advancements in capacitive and magnetic isolation, package development, and process technology
from TI can deliver power and high-speed signals safely and reliably across
the isolation barrier in industrial and automotive systems such as electric
vehicles (EVs), grid infrastructure, factory automation and motor
drives. |
What is galvanic isolation?
Galvanic isolation partitions an electrical system to prevent the flow of DC and undesirable AC between two parts, while still allowing signal and power transfer. Figure 1 illustrates two galvanically isolated circuits.
Figure 1 Low- to high-voltage galvanic
signal isolation.When GND1 is broken from GND2, I1 is galvanically isolated from I2. Since there is no commonality between GND1 and GND2, there is no common DC GND current shared through the isolation barrier. In addition to isolating shared GND connections and signal communication without conduction, it is also possible to use galvanic isolation for voltage-level shifting, since GND2 is transferable to a different floating potential relative to GND1.
High-voltage systems require additional isolation because more bidirectional signal information is communicated across the barrier. Figure 2 illustrates an example in which power, high-speed gate-driver signals and digital communication signals must all cross the isolation barrier. Many analog and digital circuits have specific bias voltage requirements where both digital signals and power cross the isolation barrier. An isolated high-resolution analog-to-digital converter (ADC) may require 3.3 V in the same system, whereas an isolated gate driver may require +15 V and –5 V. These requirements necessitate not just the transfer of signals across the isolation barrier but power as well.
Figure 2 Types of signals transferring
across an isolation barrier.Learn more about galvanic isolation in the What is Galvanic Isolation? video.
